// back to top function
lastScrollY = 0;
function heartBeat(id) {
    var diffY;
    if (document.documentElement && document.documentElement.scrollTop) {
        diffY = document.documentElement.scrollTop;
    } else if (document.body) {
        diffY = document.body.scrollTop;
    } else {
        /*Netscape stuff*/
    }
    //alert(diffY);
    percent = 0.1 * (diffY - lastScrollY);

    if (percent > 0) {
        percent = Math.ceil(percent);
    } else {
        percent = Math.floor(percent);
    }

    document.getElementById(id).style.top = parseInt(document.getElementById(id).style.top) + percent + "px";

    lastScrollY = lastScrollY + percent;
    //alert(lastScrollY);
}